Abstract

Many tele- and datacom applications require single-wavelength tunable lasers with easy wavelength control and sufficient tuning range. Such lasers can for instance be used in WDM-based optical networks or to replace fixed wavelength distributed feedback (DFB) lasers. Here we demonstrate over 7 nm continuous wavelength tuning with a novel III-V/SOI DBR laser. The laser structure consists of an SOI waveguide circuit on which a III-V tunable twin-guide (TTG) membrane is heterogeneously integrated by means of adhesive DVS-BCB bonding. The TTG membrane comprises an active layer and a tuning layer in which carriers can be injected to provide gain and phase tuning respectively. The laser cavity is formed by a broadband reflecting facet and a DBR mirror. The latter is implemented as a first-order sidewall-corrugated waveguide grating defined in the 400 nm silicon device layer. The weak sidewall-corrugation provides a narrowband spectral reflection characteristic to ensure single-mode lasing operation. It also provides an additional advantage over ring resonator configurations as for the latter a large free spectral range (FSR) is more difficult to obtain due to minimum bend radii requirements.